/*

 * jdpostct.c

 *

 * Copyright (C) 1994-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains the decompression postprocessing controller.

 * This controller manages the upsampling, color conversion, and color

 * quantization/reduction steps; specifically, it controls the buffering

 * between upsample/color conversion and color quantization/reduction.

 *

 * If no color quantization/reduction is required, then this module has no

 * work to do, and it just hands off to the upsample/color conversion code.

 * An integrated upsample/convert/quantize process would replace this module

 * entirely.

 */



#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"





/* Private buffer controller object */



typedef struct {

  struct jpeg_d_post_controller pub; /* public fields */



  /* Color quantization source buffer: this holds output data from

   * the upsample/color conversion step to be passed to the quantizer.

   * For two-pass color quantization, we need a full-image buffer;

   * for one-pass operation, a strip buffer is sufficient.

   */

  jvirt_sarray_ptr whole_image;	/* virtual array, or NULL if one-pass */

  JSAMPARRAY buffer;		/* strip buffer, or current strip of virtual */

  JDIMENSION strip_height;	/* buffer size in rows */

  /* for two-pass mode only: */

  JDIMENSION starting_row;	/* row # of first row in current strip */

  JDIMENSION next_row;		/* index of next row to fill/empty in strip */

} my_post_controller;



typedef my_post_controller * my_post_ptr;





/* Forward declarations */

METHODDEF void post_process_1pass

	JPP((j_decompress_ptr cinfo,

	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

	     JDIMENSION in_row_groups_avail,

	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

	     JDIMENSION out_rows_avail));

#ifdef QUANT_2PASS_SUPPORTED

METHODDEF void post_process_prepass

	JPP((j_decompress_ptr cinfo,

	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

	     JDIMENSION in_row_groups_avail,

	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

	     JDIMENSION out_rows_avail));

METHODDEF void post_process_2pass

	JPP((j_decompress_ptr cinfo,

	     JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

	     JDIMENSION in_row_groups_avail,

	     JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

	     JDIMENSION out_rows_avail));

#endif





/*

 * Initialize for a processing pass.

 */



METHODDEF void

start_pass_dpost (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)

{

  my_post_ptr post = (my_post_ptr) cinfo->post;



  switch (pass_mode) {

  case JBUF_PASS_THRU:

    if (cinfo->quantize_colors) {

      /* Single-pass processing with color quantization. */

      post->pub.post_process_data = post_process_1pass;

      /* We could be doing buffered-image output before starting a 2-pass

       * color quantization; in that case, jinit_d_post_controller did not

       * allocate a strip buffer.  Use the virtual-array buffer as workspace.

       */

      if (post->buffer == NULL) {

	post->buffer = (*cinfo->mem->access_virt_sarray)

	  ((j_common_ptr) cinfo, post->whole_image,

	   (JDIMENSION) 0, post->strip_height, TRUE);

      }

    } else {

      /* For single-pass processing without color quantization,

       * I have no work to do; just call the upsampler directly.

       */

      post->pub.post_process_data = cinfo->upsample->upsample;

    }

    break;

#ifdef QUANT_2PASS_SUPPORTED

  case JBUF_SAVE_AND_PASS:

    /* First pass of 2-pass quantization */

    if (post->whole_image == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    post->pub.post_process_data = post_process_prepass;

    break;

  case JBUF_CRANK_DEST:

    /* Second pass of 2-pass quantization */

    if (post->whole_image == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    post->pub.post_process_data = post_process_2pass;

    break;

#endif /* QUANT_2PASS_SUPPORTED */

  default:

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    break;

  }

  post->starting_row = post->next_row = 0;

}





/*

 * Process some data in the one-pass (strip buffer) case.

 * This is used for color precision reduction as well as one-pass quantization.

 */



METHODDEF void

post_process_1pass (j_decompress_ptr cinfo,

		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

		    JDIMENSION in_row_groups_avail,

		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

		    JDIMENSION out_rows_avail)

{

  my_post_ptr post = (my_post_ptr) cinfo->post;

  JDIMENSION num_rows, max_rows;



  /* Fill the buffer, but not more than what we can dump out in one go. */

  /* Note we rely on the upsampler to detect bottom of image. */

  max_rows = out_rows_avail - *out_row_ctr;

  if (max_rows > post->strip_height)

    max_rows = post->strip_height;

  num_rows = 0;

  (*cinfo->upsample->upsample) (cinfo,

		input_buf, in_row_group_ctr, in_row_groups_avail,

		post->buffer, &num_rows, max_rows);

  /* Quantize and emit data. */

  (*cinfo->cquantize->color_quantize) (cinfo,

		post->buffer, output_buf + *out_row_ctr, (int) num_rows);

  *out_row_ctr += num_rows;

}





#ifdef QUANT_2PASS_SUPPORTED



/*

 * Process some data in the first pass of 2-pass quantization.

 */



METHODDEF void

post_process_prepass (j_decompress_ptr cinfo,

		      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

		      JDIMENSION in_row_groups_avail,

		      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

		      JDIMENSION out_rows_avail)

{

  my_post_ptr post = (my_post_ptr) cinfo->post;

  JDIMENSION old_next_row, num_rows;



  /* Reposition virtual buffer if at start of strip. */

  if (post->next_row == 0) {

    post->buffer = (*cinfo->mem->access_virt_sarray)

	((j_common_ptr) cinfo, post->whole_image,

	 post->starting_row, post->strip_height, TRUE);

  }



  /* Upsample some data (up to a strip height's worth). */

  old_next_row = post->next_row;

  (*cinfo->upsample->upsample) (cinfo,

		input_buf, in_row_group_ctr, in_row_groups_avail,

		post->buffer, &post->next_row, post->strip_height);



  /* Allow quantizer to scan new data.  No data is emitted, */

  /* but we advance out_row_ctr so outer loop can tell when we're done. */

  if (post->next_row > old_next_row) {

    num_rows = post->next_row - old_next_row;

    (*cinfo->cquantize->color_quantize) (cinfo, post->buffer + old_next_row,

					 (JSAMPARRAY) NULL, (int) num_rows);

    *out_row_ctr += num_rows;

  }



  /* Advance if we filled the strip. */

  if (post->next_row >= post->strip_height) {

    post->starting_row += post->strip_height;

    post->next_row = 0;

  }

}





/*

 * Process some data in the second pass of 2-pass quantization.

 */



METHODDEF void

post_process_2pass (j_decompress_ptr cinfo,

		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,

		    JDIMENSION in_row_groups_avail,

		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,

		    JDIMENSION out_rows_avail)

{

  my_post_ptr post = (my_post_ptr) cinfo->post;

  JDIMENSION num_rows, max_rows;



  /* Reposition virtual buffer if at start of strip. */

  if (post->next_row == 0) {

    post->buffer = (*cinfo->mem->access_virt_sarray)

	((j_common_ptr) cinfo, post->whole_image,

	 post->starting_row, post->strip_height, FALSE);

  }



  /* Determine number of rows to emit. */

  num_rows = post->strip_height - post->next_row; /* available in strip */

  max_rows = out_rows_avail - *out_row_ctr; /* available in output area */

  if (num_rows > max_rows)

    num_rows = max_rows;

  /* We have to check bottom of image here, can't depend on upsampler. */

  max_rows = cinfo->output_height - post->starting_row;

  if (num_rows > max_rows)

    num_rows = max_rows;



  /* Quantize and emit data. */

  (*cinfo->cquantize->color_quantize) (cinfo,

		post->buffer + post->next_row, output_buf + *out_row_ctr,

		(int) num_rows);

  *out_row_ctr += num_rows;



  /* Advance if we filled the strip. */

  post->next_row += num_rows;

  if (post->next_row >= post->strip_height) {

    post->starting_row += post->strip_height;

    post->next_row = 0;

  }

}



#endif /* QUANT_2PASS_SUPPORTED */





/*

 * Initialize postprocessing controller.

 */



GLOBAL void

jinit_d_post_controller (j_decompress_ptr cinfo, boolean need_full_buffer)

{

  my_post_ptr post;



  post = (my_post_ptr)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				SIZEOF(my_post_controller));

  cinfo->post = (struct jpeg_d_post_controller *) post;

  post->pub.start_pass = start_pass_dpost;

  post->whole_image = NULL;	/* flag for no virtual arrays */

  post->buffer = NULL;		/* flag for no strip buffer */



  /* Create the quantization buffer, if needed */

  if (cinfo->quantize_colors) {

    /* The buffer strip height is max_v_samp_factor, which is typically

     * an efficient number of rows for upsampling to return.

     * (In the presence of output rescaling, we might want to be smarter?)

     */

    post->strip_height = (JDIMENSION) cinfo->max_v_samp_factor;

    if (need_full_buffer) {

      /* Two-pass color quantization: need full-image storage. */

      /* We round up the number of rows to a multiple of the strip height. */

#ifdef QUANT_2PASS_SUPPORTED

      post->whole_image = (*cinfo->mem->request_virt_sarray)

	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,

	 cinfo->output_width * cinfo->out_color_components,

	 (JDIMENSION) jround_up((long) cinfo->output_height,

				(long) post->strip_height),

	 post->strip_height);

#else

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

#endif /* QUANT_2PASS_SUPPORTED */

    } else {

      /* One-pass color quantization: just make a strip buffer. */

      post->buffer = (*cinfo->mem->alloc_sarray)

	((j_common_ptr) cinfo, JPOOL_IMAGE,

	 cinfo->output_width * cinfo->out_color_components,

	 post->strip_height);

    }

  }

}

